The United Nations Mission in Congo is launching an investigation into a deadly gunfight involving Congolese and Ugandan soldiers on Lake Albert , Monday. The discovery of oil beneath Lake Albert, which straddles Uganda and Congo , has sparked a territorial dispute between the two nations. Noel King has more in this report from Kigali.

Six civilians were killed in Monday's exchange of fire including two women and a child, the U.N. mission in Congo has said.

There have been heavily conflicting reports of the details surrounding the incident.

Witnesses to the incident told the United Nations Mission in Congo that Ugandan soldiers fired upon a Congolese passenger boat in Lake Albert. This was after two Congolese soldiers on board the boat refused to relinquish their weapons to their Ugandan counterparts.

The Ugandan military says that only two people were killed -- one soldier and one civilian.

The U.N. Mission in Congo says the precise details surrounding the incident are unclear.

U.N. military spokesman Gabriel de Brosses, spoke to VOA by phone from Kinshasa.

"We don't have any clue because we didn't have any unit nearby. We are investigating the situation," de Brosses said. "We want to know what happened and we don't know yet."

The Ugandan military linked Monday's shootout to another incident on Lake Albert , also on Monday.

The U.N. Mission seized a Ugandan oil exploration boat, which it says had strayed into Congolese waters. Ugandan officials protested the move, saying the boat was in Ugandan territory.

De Brosses told VOA that at this time, the U.N. believes the two events are unrelated.

The stakes have risen in the dispute over Lake Albert after oil was discovered there last year. Sporadic clashes between Congolese and Ugandan troops have been reported for months.

Congolese President Joseph Kabila and Ugandan President Yoweri Museveni held talks in Tanzania on September 8, agreeing to jointly explore the region for oil.